3pt1lumina Posted August 11, 2010 Report Share Posted August 11, 2010 1997 Chevy Lumina w/ a 3100. A/C blows ice cold, system is fully charged. Today I am driving home and the A/C shuts off... so I check fuses and on the pass side fender (in that fuse box) there is a 10 amp fuse that is marked "A/C" and it was blown. So I replaced it with another 10 amp, it ran ice cold for about 2 mins then popped that fuse. Where do I begin to diagnose this one? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted August 11, 2010 Report Share Posted August 11, 2010 well, that fuse only goes to a few things: the signal wire for the relay, the power wire for the relay, and the compressor control line coming from the PCM(through the relay signal wire). maybe the relay is wearing out? and after it starts heating up from flowing current, too much current is being drawn? Quote Link to comment Share on other sites More sharing options...
3pt1lumina Posted August 11, 2010 Author Report Share Posted August 11, 2010 Possibly? I wish I knew how to read that nifty diagram you posted as that seems really helpful...if I knew how to read it. Hmmm. so should I start by checking the wiring then? Or replacing the relay? I should mention I also switched the Fuel Pump Relay with the A/C Relay (the larger ones that are placed beneath the smaller amp fuses). Doesn't seem to make a difference at all. I figure if the one was bad in the A/C spot it would malfunction in the Fuel Pump Spot. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted August 11, 2010 Report Share Posted August 11, 2010 well, if swapping in the fuel pump relay in place of the a/c relay didn't fix it, then the relay itself shouldn't be suspect. Quote Link to comment Share on other sites More sharing options...
3pt1lumina Posted August 11, 2010 Author Report Share Posted August 11, 2010 I will have to look into the wiring when I have some time then. Sounds like that is the next thing to look at. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted August 11, 2010 Report Share Posted August 11, 2010 me being the cheap person i am, i would also look to be playing with the wiring. Quote Link to comment Share on other sites More sharing options...
ron350 Posted August 12, 2010 Report Share Posted August 12, 2010 Just in case you want to check the A/C compressor clutch coil should read 4 to 4.5 ohms. Quote Link to comment Share on other sites More sharing options...
3pt1lumina Posted August 13, 2010 Author Report Share Posted August 13, 2010 Good to know, thank you! I am going to go over it tomorrow night after work when I actually have some time. I will post back with what my results are. Quote Link to comment Share on other sites More sharing options...
3pt1lumina Posted August 14, 2010 Author Report Share Posted August 14, 2010 Everything seems to be ok with the wiring, I put in another fuse and it is working. Maybe the fuse I put in the first time was bad? Anyways, it's working for now so I'm going to leave it alone. Thanks for the input guys! Quote Link to comment Share on other sites More sharing options...
logikf1ve Posted August 14, 2010 Report Share Posted August 14, 2010 Must be because the fuse you got in there now came out of a Dodge! Well.. my spare fuses in my Durango... Still working I take it? Quote Link to comment Share on other sites More sharing options...
mikehutton Posted January 7, 2011 Report Share Posted January 7, 2011 Sounds Crazy stuff going on with the airconditioning unit of your car, better have it checked or burn the whole thing. _________ A/C Relay Quote Link to comment Share on other sites More sharing options...
Schurkey Posted January 7, 2011 Report Share Posted January 7, 2011 Possibly? I wish I knew how to read that nifty diagram you posted as that seems really helpful...if I knew how to read it. Easy. Start at the top right, and work downward. You replaced the toasted under-hood A/C control fuse (10 amp). That's shown in the dotted rectangle on the upper right side. It's labeled "AC CONT FUSE" The output of the fuse is a wire that is spliced to another wire, but both wires go to the second dotted rectangle, the A/C compressor relay--labeled "A/C CMPR RELAY" --one wire powers the relay itself, the relay is turned on and off by the Powertrain Control Module. The other wire is switched on and off BY the relay and powers the A/C compressor clutch. A ground (bare wire) anywhere between the relay and the compressor clutch will pop the fuse. Too little resistance in the compressor clutch will pop the fuse. A ground (bare wire) between the relay and the fuse will pop the fuse. A bare wire between the relay and the PCM will not pop the fuse, but it'll turn on the A/C; and it may do evil things to the PCM. No point in looking for problems there, since that isn't the symptom. Hmmm. so should I start by checking the wiring then? Or replacing the relay? I should mention I also switched the Fuel Pump Relay with the A/C Relay (the larger ones that are placed beneath the smaller amp fuses). Doesn't seem to make a difference at all. I figure if the one was bad in the A/C spot it would malfunction in the Fuel Pump Spot. If you've swapped relays and there's no change...the relay isn't the problem. maybe the relay is wearing out? and after it starts heating up from flowing current, too much current is being drawn? A relay does not affect the amount of current drawn except if the contacts wear they might have higher resistance and then the current flow would DECREASE. If everything is functioning properly, it's the load that determines the amount of current flow, not the relay. Just in case you want to check the A/C compressor clutch coil should read 4 to 4.5 ohms. I haven't verified the resistance spec; but yeah, that'd be the first thing to check. Quote Link to comment Share on other sites More sharing options...
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